Post by oowl on May 3, 2022 10:45:28 GMT -7
I love the originally z wreck but don’t see it super applicable due to the volume. Attenuating it? No way.
Does the half power mod really make it that usable?
I want to address the post phase inverter master volume, and explain how it works. It works particularly well on amps without negative feedback (like most of our amps), as it is in itself a sort of full signal negative feedback cycle. What happens with a PPIMV is the signal is introduced through the pot with an inverse of itself from the phase inverter. As you turn the pot down, you are canceling (phasing out) the signal out with a the inverse of the signal, which lowers the volume and eventually mutes the sound. The benefit of it being post phase inverter is that you get the gain stage of the phase inverter added into the equation, which allows for more distortion and compression, and a beefier signal as the amp is turned down. The down side of this though is if the amp isn't properly gain staged, you wind up with an overloaded phase inverter that doesn't sound good or clips unevenly. It's a balancing act of the whole preamp before it and how the phase inverter is balanced, the choice of resistance in the volume pot itself, and the tone shaping components around it.
Further, since you are lowering the signal post phase inverter and feeding less of a signal into the power tubes, you change the interaction of the previous gain stages with the power tubes, thus change the sound and the feel. Attenuators allow for that full interaction, as you are lowering the volume by dissipating the signal into heat before the speakers. Which is why Doc and Ken preferred to preserve the interaction between the two sections without adding additional circuitry inside the amp itself.